Temporal Lobe Epilepsy

What is the Temporal Lobe?

The temporal lobe serves several processing functions in the brain that mainly deal with organization of sensory input: it processes sound in the primary auditory cortex and the semantics of speech and vision. It also contains the hippocampus, which is involved with long-term memory and spatial awareness. The amygdala is also located in the temporal lobe, which processes emotions and memories. All these functions are important in studying temporal lobe epilepsy since they are affected in several ways during a temporal lobe seizure. Damage, specifically in the hippocampus, often occurs after a temporal lobe seizure.

What is TLE?

Temporal lobe epilepsy is a medical disorder that involves recurrent seizures in the temporal lobes of the brain, either in just the right hemisphere, the left hemisphere, or both.

Temporal lobe epilepsy is divided into two categories, depending where it arises:
TLE that occurs in the hippocampus and amygdala (or, on the inner side of the temporal lobe towards the center of the brain) is called Mesial Temporal Lobe Epilepsy or MTLE. TLE in the neocortex, the outer surface of the temporal lobe, is less common, and is referred to as Lateral Temporal Lobe Epilepsy, or LTLE.

In both manifestations, the natures of the seizures experienced are similar to those in general epilepsy. As mentioned on the previous page, simple partial seizures (referred to as aura) occur in only small areas of the temporal lobe and do not affect consciousness. When a simple partial seizure occurs in the temporal lobe, senesations experienced may include feelings of deja vu (experiencing something that one is sure s/he's experienced before), memory recalls, or amnesia (loss of memory). Given the function of structures located in the temporal lobe, hallucinations of smell, taste, hearing or vision may result, where patients experience sensations that are not actually there in reality.

Complex partial seizures impair consciousness and occur when a simple partial seizure spreads to a larger portion of the temporal lobe. Seizures of this magnitude in the temporal lobe may include the perception of hallucinations, aggressive behavior, changes in mood, and disturbances in memory. In addition to the loss of consciousness, there also may be automatic, jerky movements of the hands or mouth, an inability to respond, and motionless staring.

Our website will focus mostly on simple partial seizures, as the symptom of visual perceptions is one of the most common but also leads to a wide variety of unique experiences for each individual. Visual symptoms are explained further on the next page.

How is TLE different from other types of epilepsy?

Significant differences exist between sensations in patients with temporal lobe epilepsy and those who suffer from other forms of seizure disorders (Rodin et al., 1976). The differences mainly lie in cause of disease, treatment response and behavioral changes. It is also significant to note that 71% of TLE patients also tend to suffer from other types of seizure, often located elsewhere in the brain.

Research has also shown that there is a heritable predisposition to temporal lobe seizures. When combined with injury to the central nervous system (such as in convulsions during infancy) there is a higher chance of one experiencing TLE in adulthood (Rodin, et. al., 1976).